Choice for Aperiodic Versus Periodic Ratio Schedules: A Comparison of Concurrent and Concurrent‐chains Procedures

Abstract

Choice between mixed-ratio schedules, consisting of equiprobable ratios of 1 and 99 responses per reinforcement, and fixed-ratio schedules of food reinforcement was assessed by two commonly used procedures: concurrent schedules and concurrent-chains schedules. Rats were trained under concurrent fixed-ratio mixed-ratio schedules, in which both ratio schedules were simultaneously available, and under a concurrent-chains schedule, in which access to one of the mutually exclusive ratio schedules comprising the terminal links was contingent on a single "choice" response. The distribution of responses between the two ratio schedules was taken as the choice proportion under the concurrent procedure, and the distribution of "choice" responses was taken as the choice proportion under the concurrent-chains procedure. Seven of eight rats displayed systematic choice; of those, each displayed nearly exclusive choice for fixed-ratio 35 to the mixed-ratio schedule under the concurrent procedure, but each displayed nearly exclusive choice for the mixed-ratio schedule to fixed-ratio 35 under the concurrent-chains procedure. Thus, preference for a fixed or a mixed schedule of reinforcement depended on the procedure used to assess preference.

The role of context in risky choice

“…Several non-human experiments have shown significant preference for the variable alternative over the fixed alternative when the two are equated (Fantino, 1967, Sherman & Thomas, 1968; Cicerone, 1976; Rider, 1983). In generalizing the results to humans, the experiment sought to discover what contingencies facilitate these patterns in choice behavior.…”

“…Much work has been done with humans on decision-making under uncertainty, for example Prospect-Theory (Kahnemann & Tversky, 1979) while behavioral studies have addressed this issue with non-human subjects (Fantino, 1967; Sherman & Thomas, 1968; Rider, 1983). While there is no standard definition, the term “risky choice” in the current experiment is empirically defined as a choice between two options, one fixed and the other variable (in terms of the reinforcement schedule parameters, not reinforcer amount).…”

“…Behavioral experiments have studied risky choice by offering the choice between two routes to reinforcement, one fixed and the other variable, in terms of time-based delay (Cicerone, 1976; Locey, Pietras, & Hackenberg, 2009) or response requirement (Fantino, 1967; Sherman & Thomas, 1968; Rider, 1983). Results from non-human studies have consistently found strong preference for the “variable” outcome, when overall reinforcement rate was held constant between the two outcomes.…”

Choice between variable and fixed cocaine injections in male rhesus monkeys

“…Sample trials were followed by choice trials, during which both sets of white lights were illuminated, and consequences of associated with both levers were available. For choice trials, a single response on either lever darkened the lights on the opposite lever to prevent switching (e.g., Rider 1983), and responses to that lever were recorded but had no other programmed consequences.…”

The Science of Decision-making: Behaviours Related to Gambling

“…In the earliest demonstration of this effect, Hermstein (1964) asked pigeons to choose between an outcome providing food reward on a fixed-interval (FI) 15-sec schedule in which reward occurred for the first response after 15-sec had elapsed and an outcome providing food on a variable-interval (VI) 15-sec schedule in which reward occurred for the first response after a variable period of time, averaging 15-sec. Herrnstein Such risk-preference with reinforcer-delay risk has been found despite differences in procedures, reinforcement schedules, types of reinforcement and the species under investigation (Aheam et al, 1992;Kacelnik, 1995, 1997;Case et al, 1995;Cicerone, 1976;Davison, 1969Davison, , 1972Frankel and Vom Saal, 1976;Gibbon et al, 1988;Hursh and Fantino, 1973;Kendall, 1987Kendall, , 1989Killeen, 1968;Logan, 1965;Morris, 1986;Navarick and Fantino, 1975;Pubols, 1962;Rider, 1983;Sherman and Thomas, 1968;Zabludoff et al, 1988).…”